Fatal error in ENFORCE rule at compile time.

[stefjoosten]

What happened

I was experimenting with enforcement rules in RAP4, when suddenly I got a fatal error. Since the script was without type errors, I expected it to pass fluently through the compiler.

The screenshot tells the entire story:

This is a fatal error, so this clearly is a bug.

Reproducing the error

1. Log in to https://rap.tarski.nl
2. Create a new script with the following contents:

    CONTEXT Issue1419
    
    CLASSIFY Ss ISA S
    CLASSIFY Uu ISA U
    
    RELATION r[S*T]
    RELATION s[T*U]
    RELATION t[Ss*Uu]
    
    ENFORCE t >: r;s
    
    ENDCONTEXT
   

3. Compile this script
   Lo and behold, the fatal error appears.

Symptoms

In a first attempt to analyze this error, I noticed that the following script compiles without errors:

CONTEXT Issue1419

CLASSIFY Ss ISA S
CLASSIFY Uu ISA U

RELATION r[S*T]
RELATION s[T*U]
RELATION t[Ss*Uu]

ENFORCE t >: I[Ss];r;s;I[Uu]

ENDCONTEXT

[hanjoosten]

This obviously is a typecheck error, similar to the one @sjcjoosten fixed with #1392. As he commented in that PR, he said that there were probably fewer errors than before.
@sjcjoosten , could you please have a look at this new bug?

[stefjoosten]

I ran into the same mistake today, when using Ampersand-v4.6.2, which was called FROM ampersandtarski/prototype-framework:v1.14