"Control Variables" Event Crashing Game

I'm a new user to this, so I'm sorry if this is a simple fix or a problem with how I'm understanding something. While trying to make a bank, I found that I needed to store the current gold as a variable so that I could determine whether the amount that the player wanted to deposit is less than the amount that they currently had. The problem is that when I try to use the control variable option in the event creator to set a variable to the current gold value, and then speak to that person in-game, the game crashes with this error:

Script 'Game_Interpreter' line 649: NoMethoddError occurred.

undefined method '[]='for #<Game_Variables0x8baa970 @data=[]>

I'm not familiar with the language in the script, but there seems to be an error in that section where the event references. Is this a common problem? Is there some way to fix it or am I understanding the function of the Control Variables option wrong?

Does this happen with a new project?

Surprisingly, no. I copied my bank event directly into a new project and it works perfectly. I don't think I changed anything in the script that would cause this- is there a simple way to replace the script in my original project with my script in the new project?

Edit: Never mind. I just found the script file in the clean project and replaced the old one, and that seems to have worked fine. Thanks for the help. :)

Ah yes, I was going to recommend that. If a clean project works, you're either using a custom script that is producing the error, or somehow the original scripts got corrupted, So it's a good idea to copy them over, or to remove the custom script causing the error. Glad you figured it out yourself though!

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