compile_commands.json is not generated if cli run with --only-compilation-database ends in error

[ag88]

Bug Report

Current behavior

this issue is discovered in Arduino IDE 2.0 beta 4 found here
arduino/arduino-ide#220 (comment)

if arduino-cli compile is run with --only-compilation-database ends in error, compile_commands.json is not generated

however if arduino-cli compile is run without --only-compilation-database the build completes, though with a success : false status and a detailed compile_commands.json file is successfully generated

the complete details is in the Arduino IDE issue comment link above.

Expected behavior

the missing compile_commands.json file causes definition and symbol lookup to fail in Arduino IDE 2.0.
it would seem --only-compilation-database needs to run to completion even if encountering some errors as otherwise compile_commands.json is not generated

Environment

• CLI version (output of arduino-cli version):
• arduino-cli version
  arduino-cli alpha Version: 0.17.0 Commit: ab58758 Date: 2021-03-17T15:10:16Z
• OS and platform: linux opensuse

Additional context

the problem is discovered in Arduino IDE 2.0 beta4