chore: demo should panic when errors occur

[seeflood]

What this PR does:

• demo should panic when errors occur
• fix minio error messages
• delete redundent demos

Which issue(s) this PR fixes:

Fixes #586
Fixes #649

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov]

Codecov Report

Merging #650 (0101ca1) into main (1576bc7) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #650   +/-   ##
=======================================
  Coverage   60.92%   60.92%           
=======================================
  Files         120      120           
  Lines        6377     6377           
=======================================
  Hits         3885     3885           
  Misses       2120     2120           
  Partials      372      372           

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