Super Dev Mode pauses on “invisible” breakpoints & then shows blank screen

[divyanshu kumar]

I’m running GWT Super Dev Mode via ant devmode (with my main server already up in another terminal). The code server launches fine, and I click my “Dev Mode On” bookmarklet in Chrome. Compilation proceeds without errors, but then DevTools immediately pops up saying “paused on breakpoint.” I didn’t set any breakpoints.

Steps I've already taken:

• Disabled all breakpoints in Chrome DevTools (Sources ➤ 🔴 Deactivate Breakpoints).

• Cleared any marker breakpoints in my code editor.

• Toggled Dev Mode off and back on again—but now I just see a blank screen.

Logs from the terminal during this process:

[java] GET /sourcemaps/ode/D4A92ECC870BD56410DE88EB04617475_sourcemap.json
[java] sent source map for module 'ode' in 169 ms
[java] GET /recompile/ode
[java] Job com.google.appinventor.YaClient-dev_1_2
[java] starting job: com.google.appinventor.YaClient-dev_1_2
[java] binding: locale=en
[java] binding: user.agent=safari
[java] skipped compile because no input files have changed
[java] 0.108s total -- Compile completed
[java] GET /sourcemaps/ode
[java] [WARN] ignored get request: /sourcemaps/ode
[java] [WARN] not handled: /sourcemaps/ode

Any guidance or troubleshooting steps would be hugely appreciated!
Thanks in advance 🙏

[Craig Mitchell]

In the Chrome Debugger, does it tell you where it's stopped in the sources tab?

Someone might have added GWT.debugger(); to the code.

I actually can't remember what the point of the code servers "Dev Mode On / Off" is.  I never use it.  The code server just does its thing automatically for me.

[Colin Alworth]

Having seen your StackOverflow post with added detail, I thought I'd answer here too, as it might help anyone else who runs into this.

In Super Dev Mode, the Java `assert` keyword compiles roughly to
if (!<condition>) {

    debugger;

    throw AssertionError(<message>);
}

This way, if you have a debugger running, you can catch it as it fails this check and see what happened to cause that failure. If not, you'll just get the AssertionError thrown and have to handle it.

Assertions are disabled by default in production, but can be enabled if desired.

They are always enabled in SDM at this time.

[divyanshu kumar]

You're right, thanks so much for the response! That helped me resolve the issue. 🙌