JHipster gulp build not generating app.js for production - jhipster

Question

My application runs fine in development. When I run the production build, app.js is missing from the build/lib/www/app folder. Could anyone offer some insight on how to track down what is going wrong with my build?
Thanks.
Update:
I walked through all the gulpfile trying to understand what was going on and finally got to the build function called at the end of the assets:prod task. Within that function I replaced the templates variable in the line
.pipe(gulpIf('**/app.js', footer(templates)))
with a test string and it works. So now I'm down to working out which template of many is causing the problem. What a pain. Is there a way to get gulp to give you a little more info such as some of the chars near where the error occurred?
./gradlew -Pprod clean bootRepackage
Starting a Gradle Daemon (subsequent builds will be faster)
The Task.leftShift(Closure) method has been deprecated and is scheduled to be removed in Gradle 5.0. Please use Task.doLast(Action) instead.
at gatling_b4a4yvzsw9z41nm1decp5w4n3.run(/Users/jreymann/projects-java/us.netblue/gradle/gatling.gradle:23)
:clean
:cleanResources UP-TO-DATE
:bootBuildInfo
:bower
:nodeSetup SKIPPED
:npmSetup SKIPPED
:npmInstall UP-TO-DATE
:gulpBuildWithOpts
[12:29:58] Using gulpfile ~/projects-java/us.netblue/gulpfile.js
[12:29:58] Starting 'clean'...
[12:29:58] Finished 'clean' after 4.63 ms
[12:29:58] Starting 'build'...
[12:29:58] Starting 'copy:fonts'...
[12:29:58] Starting 'copy:common'...
[12:29:58] Starting 'inject:vendor'...
[12:29:58] Starting 'ngconstant:prod'...
[12:29:58] Finished 'ngconstant:prod' after 23 ms
[12:29:58] gulp-inject 1 files into vendor.scss.
[12:29:58] Finished 'copy:common' after 78 ms
[12:29:58] gulp-inject 19 files into index.html.
[12:29:58] Finished 'inject:vendor' after 79 ms
[12:29:58] Finished 'copy:fonts' after 98 ms
[12:29:58] Starting 'copy'...
[12:29:58] Finished 'copy' after 19 μs
[12:29:58] Starting 'inject:app'...
[12:29:58] gulp-inject 143 files into index.html.
[12:29:58] Finished 'inject:app' after 168 ms
[12:29:58] Starting 'inject:troubleshoot'...
[12:29:58] gulp-inject Nothing to inject into index.html.
[12:29:58] Finished 'inject:troubleshoot' after 2.07 ms
[12:29:58] Starting 'images'...
[12:29:58] Starting 'sass'...
[12:29:58] Starting 'html'...
[12:29:58] Starting 'copy:swagger'...
[12:29:58] Starting 'copy:images'...
[12:29:58] Finished 'copy:images' after 8.98 ms
[12:29:59] Tested 18 tests, 18 passes, 0 failures: PASS
[12:29:59] gulp-imagemin: Minified 6 images (saved 6.79 kB - 17%)
[12:29:59] Finished 'images' after 459 ms
[12:29:59] Finished 'sass' after 492 ms
[12:29:59] Starting 'styles'...
[12:29:59] Finished 'styles' after 2.21 ms
[12:29:59] Finished 'html' after 527 ms
[12:29:59] Finished 'copy:swagger' after 527 ms
[12:29:59] Starting 'assets:prod'...
[12:30:12] Finished 'assets:prod' after 13 s
[12:30:12] Finished 'build' after 14 s
:processResources
:compileJava
[Fatal Error] shrinkwrap-descriptors-bom-2.0.0-alpha-3.pom:130:6: The processing instruction target matching "[xX][mM][lL]" is not allowed.
[Fatal Error] shrinkwrap-descriptors-bom-2.0.0-alpha-3.pom:130:6: The processing instruction target matching "[xX][mM][lL]" is not allowed.
[Fatal Error] commons-lang3-3.4.pom:772:1: Content is not allowed in trailing section.
[Fatal Error] commons-parent-39.pom:1506:5: The markup in the document following the root element must be well-formed.
[Fatal Error] commons-lang3-3.4.pom:772:1: Content is not allowed in trailing section.
[Fatal Error] commons-parent-39.pom:1506:5: The markup in the document following the root element must be well-formed.
[Fatal Error] commons-lang3-3.4.pom:772:1: Content is not allowed in trailing section.
:compileScala UP-TO-DATE
:classes
:findMainClass
:war
[Fatal Error] commons-lang3-3.4.pom:772:1: Content is not allowed in trailing section.
[Fatal Error] commons-lang3-3.4.pom:772:1: Content is not allowed in trailing section.
:bootRepackage
BUILD SUCCESSFUL
If I run the gulp build individually I get:
gulp build
[12:05:12] Using gulpfile ~/projects-java/us.netblue/gulpfile.js
[12:05:12] Starting 'clean'...
[12:05:12] Finished 'clean' after 21 ms
[12:05:12] Starting 'build'...
[12:05:12] Starting 'copy:fonts'...
[12:05:12] Starting 'copy:common'...
[12:05:12] Starting 'inject:vendor'...
[12:05:12] Starting 'ngconstant:prod'...
[12:05:12] Finished 'ngconstant:prod' after 25 ms
[12:05:12] gulp-inject 1 files into vendor.scss.
[12:05:12] Finished 'copy:common' after 80 ms
[12:05:12] gulp-inject 19 files into index.html.
[12:05:12] Finished 'inject:vendor' after 80 ms
[12:05:12] Finished 'copy:fonts' after 104 ms
[12:05:12] Starting 'copy'...
[12:05:12] Finished 'copy' after 24 μs
[12:05:12] Starting 'inject:app'...
[12:05:13] gulp-inject 143 files into index.html.
[12:05:13] Finished 'inject:app' after 179 ms
[12:05:13] Starting 'inject:troubleshoot'...
[12:05:13] gulp-inject Nothing to inject into index.html.
[12:05:13] Finished 'inject:troubleshoot' after 2.19 ms
[12:05:13] Starting 'images'...
[12:05:13] Starting 'sass'...
[12:05:13] Starting 'html'...
[12:05:13] Starting 'copy:swagger'...
[12:05:13] Starting 'copy:images'...
[12:05:13] Finished 'copy:images' after 7.44 ms
[12:05:13] Tested 18 tests, 18 passes, 0 failures: PASS
[12:05:13] gulp-imagemin: Minified 6 images (saved 6.79 kB - 17%)
[12:05:13] Finished 'images' after 439 ms
[12:05:13] Finished 'sass' after 483 ms
[12:05:13] Starting 'styles'...
[12:05:13] Finished 'styles' after 1.42 ms
[12:05:13] Finished 'html' after 511 ms
[12:05:13] Finished 'copy:swagger' after 514 ms
[12:05:13] Starting 'assets:prod'...
[12:05:26] gulp-notify: [JHipster Gulp Build] Error: Unexpected token .
[12:05:26] Finished 'assets:prod' after 13 s
[12:05:26] Finished 'build' after 14 s

Answer 1

After some hours of trying each template one at a time, I finally found the problem as being a typo in a template where there was a $ instead of $. That threw an the vague error in the JS related subtask in the build function.

Answer 2

If you open gulpfile.js there is a gulp task called 'html'.
If you run this task from the terminal by typing "gulp html" it will generate a file called 'templates.js' in 'target/tmp' folder.
This file has multiple $templateCache.put lines.
One of those lines maybe causing the error.
Run your application in PROD profile and keep the server running.
Delete almost all of the $templateCache.put lines except for homepage line in templates.js and run 'gulp build'.
Now hard refersh the browser and check if you are able to see the homepage.
If the homepage and the other lines are not causing the error you will see the homepage.
Now add back some of those deleted $templateCache.put lines to templates.js and run 'gulp build' again.
Repeat this process till you fine the line that is causing the issue.
Once you find out that line check the html page it mentions and try and remove all comments in that html file.
Some code in that html file maybe causing the issue.
Hope this helps.