Fix #1655: SENTRY_DSN cannot be defined

[krombel]

Fixes #1655

[DanielMcAssey]

Just FYI, docker-compose defaults to 0 if those env variables arent set, im not sure if .Env.SENTRY_DSN evaluates to true in that regard

[krombel]

In that case the library handles that variable as a number. And 0 is handled as false in an if case.

For reference: http://masterminds.github.io/sprig/defaults.html (the underlying library which handles that parsing)

The relevant parts

The definition of “empty” depends on type:

Numeric: 0
[...]

Note that in Go template conditionals, emptiness is calculated for you. Thus, you rarely need if empty .Foo. Instead, just use if .Foo.

[DanielMcAssey]

Perfect! Looks good to me, ill close my PR