chrome.tabs.executeScript is unreliable - google-chrome-extension

Question

I'm trying to inject content script dynamically so I'm using the documented chrome.tabs.executeScript method for this.
However, unlike embedded content scripts (defined in the manifest) the dynamic script runs on a random basis while I need to be sure it runs everytime.
Basically I listen for tab update events in background script and execute dynamic content script on every "loading" event
What I've noticed is that the behavior seems to be connected with page/script loading timing - if page loading completes before the script execution, the script won't run, otherwise it seems to work as expected.
Though this is just a guess based on the observation and if you have any other ides of what is going on here feel free to share your thoughts.
Is there any ways to ensure dynamic script executes 100% of the time despite of any circumstances?
Here is the log sequence in which script doesn't run:
loading: changeInfo = {status: "loading"}
loading: start. sender.tab.id = 1454
loading: start script loading
loading: code size = 4190306 bytes
loading: changeInfo = {status: "complete"} <- page loading completed
loading: time to execute script = 945 <- script execution completed
And here is the code snippet:
chrome.tabs.onUpdated.addListener(function (tabId, changeInfo, tab) {
console.log("loading: changeInfo = ", changeInfo)
if (changeInfo.status !== "loading") {
console.log("loading: skip");
return;
}
console.log("loading: start. sender.tab.id = ", tabId)
console.log("loading: start script loading")
var timerStart = Date.now();
console.log("loading: code size = ", byteCount(scriptCode), " bytes")
chrome.tabs.executeScript(tabId,
{
code: scriptCode,
runAt: "document_idle"
}, function (response) {
console.log("loading: time to execute script = ", Date.now() - timerStart)
var err = chrome.runtime.lastError;
console.log("loading: response = ", response, ", err = ", err)
});
});
There are also no errors in the log
One more thing to add - if I wrap chrome.tabs.executeScript in setTimeout with something like 2000ms delay this guarantees script will never run which suggests timing issue.

Answer 1

Ok, that was dumb - the problem appeared to be in the dynamic script code itself: the main logic was executed in the onload callback and was never run if the script loads after the onload:
window.addEventListener("load", mainLogic, false);
removing the callback and running mainLogic() directly fixed the issue.
I'll leave it here in case someone did the same mistake as I did.