Fix the context_lines option not skipping reading the source code if its value is set to null

[ste93cry]

Q	A
Branch?	2.3
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
License	MIT

I noticed that setting the context_lines option to 0 null does not prevent the source code from being read and attached to each frame of a stacktrace, but the documentation says it should work this way. In addition to this, the validation was missing leading to bad things when such option was set to a value lower than zero, so I took the time to fix this too.

[Jean85]

Looking at the docs, this seems the wrong behavior: https://docs.sentry.io/platforms/php/#context_lines

If null is set as the value, no source code lines will be added to each stack trace frame. By default this option is set to 3.

I tend to agree with this, because it allows to have just the user to have only the offending rule; so, null is "Do not upload my source code" where instead 0 is "upload only the offending line, no context lines".

[ste93cry]

so, null is "Do not upload my source code" where instead 0 is "upload only the offending line, no context lines".

While you are right that the documentation says a different thing, and from what I see the Go SDK follows the same reasoning, I don't think that it really makes sense that setting the option to 0 still sends the offending line. As there is there is no distinction for the user between pre/post context lines and the context line itself, as a user I would not expect that 0 means 1 and null means 0, wouldn't you?

[Jean85]

It seems we're not agreeing on the meaning of "context". Context is the surrounding of the subject, so in this case the lines above and below the one in the stacktrace. That's why I consider that the correct approach.

@HazAT can you weight in here? Is this interpretation the right and meant one?

[ste93cry]

Context is the surrounding of the subject, so in this case the lines above and below the one in the stacktrace.

After reading the linked article I now think that you are proven right, but to be on the safe side let's wait anyway for a final word by @HazAT

[HazAT]

So the context_lines are really focused around the pre_context and post_context. So setting this to 0 on makes pre_context & post_context empty.
null should not even send the offending line.

[stayallive]

Good change/fix 👍