Fix crash when opening a new file

[Jan9103]

When opening a not existent file (example git checkout master; cargo run foo.txt) it will error out since the metadata check does not handle the case.

I'm not good at rust or too familiar with this project, but here's a working patch.

[codecov]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (8966c46) 48.70% compared to head (6359161) 48.51%.

Files	Patch %	Lines
src/editor.rs	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #287      +/-   ##
==========================================
- Coverage   48.70%   48.51%   -0.19%     
==========================================
  Files          11       11              
  Lines        1043     1047       +4     
==========================================
  Hits          508      508              
- Misses        535      539       +4     

Flag	Coverage Δ
wasm32-wasi	49.95% <0.00%> (-0.20%)	⬇️
x86_64-apple-darwin	50.04% <0.00%> (-0.20%)	⬇️
x86_64-pc-windows-gnu	0.20% <0.00%> (-0.01%)	⬇️
x86_64-unknown-linux-gnu	49.95% <0.00%> (-0.20%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.