v0.21.0

Changelog

81f153e fix missing format arg
8cac76d fix: Avoid panic on run without args
2072059 fix: Avoid panic on variable without type attribute
fc5484f fix: Try to print errors in more cases
6bb9498 feat: Set VARIANT_TRACE envvar to enable tracing
7646b84 doc: Testing Framework
b93fa48 fix: Logging without forward block
94a6ff9 feat: Interactive Commands