GWT works great in Hosted Mode, and Compiles without error -- but its JS files are buggy

I have no errors show up in either the compilation or the hosted mode process, but the JS that GWT creates contain errors that disallow the proper rendering of the website. How can this happen? Is this a problem with the compiler?

FireBug is giving me nothing, no errors at all.

But I don't know where to go from here or what more information to give you all, since I can't effectively debug JS like this. More fundamentally, I just don't understand why GWT is giving me JS that doesn't work.

EDIT: I didn't really know what Pretty and Detailed meant until now. Thanks for pointing m开发者_运维问答e to this. What I get now is http://i.imgur.com/qUyNb.png.

I'm not sure where to go from here.

EDIT 2: Here is the final image I will post (I promise!): http://i.imgur.com/ZVQVW.png. This is the pretty output. The error reads: "Uncaught com.google.gwt.core.client.JavaScriptException (TypeError): Cannot call method 'isString' of null (anonymous function)."

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The resolution to this issue was the realization that isString was not a JNSI method, but instead a method I wrote in a try / catch block. This was the code that tripped me up:

try{something that will create a NullPointerException}
catch(NullPointerException npe){npe.printStackTrace()}

@Luismahou's link above said the following about error-catching in GWT:

Exceptions: try, catch, finally and user-defined exceptions are supported as normal, although Throwable.getStackTrace() is not meaningfully supported in production mode. Note: Several fundamental exceptions implicitly produced by the Java VM, most notably NullPointerException, StackOverflowError, and OutOfMemoryError, do not occur in production mode as such. Instead, a JavaScriptException is produced for any implicitly generated exceptions. This is because the nature of the underlying JavaScript exception cannot be reliably mapped onto the appropriate Java exception type.

I think what happened is that my try block threw a NullPointerException, which was represented as a JavaScriptException and was uncaught by the catch block. Lesson learned: don't catch NullPointerExceptions, StackOverflowErrors, and OutOfMemoryErrors in GWT.