Return Result from fallible registry functions

This updates the registry add_* functions to return a Result instead of
a bool on failure to force handling errors. The placeholder error is
used temporarily.

Change-Id: If9db8c2a442f75f2a0746e1774b7b3c6455bcbe5
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/qg/+/125211
Commit-Queue: Alexei Frolov <frolv@google.com>
Reviewed-by: Erik Gilling <konkers@google.com>
2 files changed
tree: 8a0c7ce2f3bafa1a1119e177c6942c6e31828295
  1. examples/
  2. qg/
  3. qg-cli/
  4. tools/
  5. .gitignore
  6. Cargo.toml
  7. rustfmt.toml