What are the reasons for : java.lang.NumberFormatException

I searched about it in Community before searching,but only one topic was related to it but was different than my error.
I have installed Appinventor Offline Sources because in my building there is problem in internet connection and I am not able to create apps online,so i tried this way and thought to add one Component which i need also,after adding it and its visible Component i build the sources and ran it but I can’t even open any project
my error is
java.lang.NumberFormatException: For input string: “”
what can be the reason of this error if i have not edit anything in appinventor sources except adding a component

Ask the developer of the offline version you are using?

i am using latest appinventor source

The problem lies somewhere in the changes you made. You will need to share the code you added for us to help you with specifying where in the code this error is occurring.

as i said did no changes in files
i just added Component java file
i noticed something that i Downloaded sources on May 5,maybe there is a fix on May 7,maybe it can fix it.any suggestion

will adding this work?

after removing the Component and its visible supporter file
i finally succeeded in opening the project but getting error while trying to drag Components
got same error but not exception name is UmbrellaException

i have figured out that latest appinventor sources have problem.is there any way to download 2-3months old sources?

I think your best approach is to download a predefined package.

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the most up to date offline server AI2 Offline by ramiro-pa (latest version nb183c as of Apr 18, 2020)
you can find here AI2Offline - Browse Files at SourceForge.net


Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by Taifun.

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Thank you everyone ,I cannot edit it according to me but then also its best for me in slow internet connection

Can you share your code ?