Read SENTRY_RELEASE and other env vars in the dart package

[bruno-garcia]

Discovering release via env var is also useful in the core dart package to be used by Dart VM projects.

[marandaneto]

@ueman this issue is about

sentry-dart/flutter/lib/src/default_integrations.dart

Lines 362 to 369 in fecf459

	// for non-mobile builds, we read the release and dist from the
	// system variables (SENTRY_RELEASE and SENTRY_DIST).
	options.release = const bool.hasEnvironment('SENTRY_RELEASE')
	? const String.fromEnvironment('SENTRY_RELEASE')
	: options.release;
	options.dist = const bool.hasEnvironment('SENTRY_DIST')
	? const String.fromEnvironment('SENTRY_DIST')
	: options.dist;

ideally, for non Android/iOS, this should work for the Dart package too, maybe moving this around

https://github.com/getsentry/sentry-dart/blob/main/dart/lib/src/sentry.dart#L64-L72

[ueman]

Thanks, I already figured that out, though.

One question I have is the order of precedence.
Is it environment variables over SentryOptions over values read from package_info or device?

[marandaneto]

see here https://docs.sentry.io/platforms/dart/configuration/options/

it depends on the property tbh, eg
options.dsn has precedence over SENTRY_DSN

SENTRY_ENVIRONMENT has precedence over options.environment

package_info has precedence over SENTRY_RELEASE, SENTRY_RELEASE has precedence over options.release (this is tricky as package_info is an integration and executed only later)

dist isn't documented but I guess it'd be similar to environment