fix: properly serialize errors sent to logger

[adalinesimonian]

Encountered in #281

Prior to this fix, in certain instances, logged errors would be missing critical information, such as message or stack.

Example, prior to fix:

[Debug - 9:24:33 a.m.] [language-server] Log message | error: {}

Example, after fix:

[Debug - 9:24:33 a.m.] [language-server] Log message | error: {"name":"Error","message":"…","stack":"…"}