better errors here

[sezna]

petr/petr-typecheck/src/error.rs

Lines 18 to 23 in e4b9cd0

	// TODO better errors here
	#[error("This type references itself in a circular way")]
	CircularType,
	#[error("Type {1} is not castable to type {0}")]
	InvalidTypeUpdate(String, String),
	}

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This issue was generated by todo-issue based on a TODO comment in e4b9cd0. It's been assigned to @sezna because they committed the code.