[BUG] Display a message that an object file cannot be decompiled

[1superchip]

Describe the bug
When the decompile button is pressed and the scratch is an object file rather than an assembly file, the decompile button opens the decompile tab and spins as if its loading.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://decomp.me/scratch/z3I55
2. Click on Decompile
3. The spin icon just spins as if its working

Expected behavior
Provide a message that an object file cannot be decompiled rather than endlessly spin as if its working.

Screenshots
If applicable, add screenshots to help explain your problem.

Scratches
https://decomp.me/scratch/z3I55
https://decomp.me/scratch/Otqco
https://decomp.me/scratch/d8G2o

[ethteck]

related: #1286