Codespace prototype fails to launch after some successful runs.

[stefjoosten]

What happened

I wrote a prototype to execute in Codespace from the project-template repo. All went well, but the fourth or fifth deployment. All of a sudden the prototype wouldn't come up anymore. I got a white screen instead of the application. I did several attempts, all of which gave more or less the same response on the console:

Observations that might help to diagnose the problem

Note: the build stage made me wait for the rollout until the time limit expired:

@stefjoosten ➜ /workspaces/project-template (master) $ kubectl rollout status deployment/prototype --timeout=300s
Waiting for deployment "prototype" rollout to finish: 0 of 1 updated replicas are available...

Note: the script contains a syntax error on lines 85 through 93. A right square bracket is missing on line 93:

INTERFACE Identifiers FOR User: "_SESSION"[SESSION] BOX
   [ Identifiers : V[SESSION*Identifier] BOX
       [ id : I
       , name : name
       , "Prefix name" : as~
       , "declaration in Module" : declares~
       , "used in Module" : uses~
       , entity : refer
       ]

What I expected

I expected a robust service.

Version of ampersand that was used

Steps to reproduce

1. navigate to https://github.com/AmpersandTarski/project-template
2. start a codespace
3. Put the script (below) in the VS-code window for ./project/main.adl.
4. build using command Ampersand: generate prototype
5. connect by clicking Open in Browser.

Screenshot / Video

Context / Source of ampersand script

CONTEXT Namespaces IN ENGLISH MARKDOWN
PURPOSE CONTEXT Inclusion 
{+ When one module includes another, name conflicts may arise.
A name conflict occurs when an identifier refers to more than one entity.
To prevent this, we define name spaces and conventions for referring to entities in other modules.
+}

PURPOSE CONCEPT Identifier 
{+ Identifiers refer to entities that are defined in some module.
We consider identifiers in a different location to be different identifiers, even though they may have the same name or refer to the same entity.
The name of an identifier is constrained by the language syntax, which is not relevant for the purpose of avoiding name conflicts.
+}
CONCEPT Identifier "An identifier is the occurrence of a string in a module that refers to an entity." ""
CONCEPT Entity "An entity is something that is defined in a module, to which an identifier can refer."

PURPOSE RELATION uses
{+ The relation `uses` registers the identifiers that a module uses to refer to declarations.
In this context, we use it to establish the absence of name conflicts.
+}
RELATION uses[Module*Identifier]

PURPOSE RELATION declares
{+ The relation `declares` registers the identifiers that each module declares,
to which the compiler matches identifiers used.
+}
RELATION declares[Module*Identifier]

PURPOSE RELATION sees
{+ The relation `sees` specifies which identifiers a module can see.
This includes identifiers in other modules it imports, as defined in rule "ENFORCE sees".
+}
RELATION sees[Module*Identifier]

PURPOSE RELATION refer
{+ The relation `refer` specifies the entities that an identifier refers to.
to which the compiler matches identifiers used.
This relation is not univalent because we want to present name conflicts to the user.
+}
RELATION refer[Identifier*Entity] [TOT]

PURPOSE RELATION name
{+ The relation `name` specifies the name of an identifier as the compiler has observed in the source code.
This allows us to distinguish between different identifiers with the same name, i.e. different occurrences.
+}
RELATION name[Identifier*Name] [UNI,TOT]

PURPOSE RULE AllDeclared
{+ A module must see every declaration that its identifiers refer to. +}
RULE AllDeclared : (I/\uses~;uses);refer |- uses~;sees;refer

PURPOSE RULE NoConflict
{+ We want identifiers to refer to at most one entity, to prevent ambiguity.
This rule is implemented as "RULE NoConflict" to obtain a useful violation message for the programmer.
+}
ROLE User MAINTAINS NoConflict
RULE NoConflict : refer;-I[Entity];refer~ |- name;-I[Name];name~
MESSAGE "Name conflict:"
VIOLATION (TXT "Identifier ", SRC name, TXT " refers to entities ", SRC refer, TXT " and ", TGT refer, TXT ".")

PURPOSE RELATION from
{+ Suppose Module A contains the following statement.

INCLUDE B

The relation `from` specifies that this statement is made in Module A.
The relation `incl` specifies that this statement includes Module B.
+}

RELATION from[IncludeStatement*Module]
RELATION incl[IncludeStatement*Module]

RELATION as[IncludeStatement*Identifier]

VIEW Prefixed : Prefixed(l,TXT ".",r)
VIEW Identifier : Identifier(name)
VIEW IncludeStatement : IncludeStatement(from, TXT ": INCLUDE ", incl, TXT " AS ",as)
CLASSIFY Prefixed ISA Identifier
RELATION l[Prefixed*Identifier] [UNI,TOT]
RELATION r[Prefixed*Identifier] [UNI,TOT]

ENFORCE sees := declares
                \/ incl~;(as;l~/\from;sees;r~)
                \/ incl~;(I-as;as~);from;sees

INTERFACE Identifiers FOR User: "_SESSION"[SESSION] BOX
   [ Identifiers : V[SESSION*Identifier] BOX
       [ id : I
       , name : name
       , "Prefix name" : as~
       , "declaration in Module" : declares~
       , "used in Module" : uses~
       , entity : refer
       ]
INTERFACE Includes FOR User: "_SESSION";V[SESSION*Identifier];(I/\as~;as) BOX
       [ id : I
       , name : name
       , "Include statement" : as~
       , l : l~
       ]
INTERFACE Declarations FOR User: "_SESSION";V[SESSION*Identifier];(I/\declares~;declares) BOX
       [ id : I
       , name : name
       , declares : declares~
       , seen : sees~
       , refer : refer
       , l : l~
       , r : r~
       , "in" : I[Prefixed]
       ]
INTERFACE References FOR User: "_SESSION"[SESSION];V[SESSION*Identifier];(I/\uses~;uses) BOX
       [ id : I
       , name : name
       , "used by" : uses~
       , seen : sees~
       , refer : refer
       , l : l~
       , r : r~
       , "in" : I[Prefixed]
       ]
INTERFACE Entities FOR User: "_SESSION";V[SESSION*Entity] BOX
       [ id : I
       , "referred by" : refer~
       , "Defined in" : refer~;declares~
       , "Used in" : refer~;uses~
       , "declared by" : refer~;declares~
       ]
INTERFACE Modules FOR User: "_SESSION";V[SESSION*Module] BOX
       [ id : I
       , "Include statement" : incl~
       , from : incl~;from
       , uses : uses
       , declares : declares
       , sees : sees
       ]
INTERFACE Other FOR User: "_SESSION"[SESSION] BOX
   [ IncludeStatements : V[SESSION*IncludeStatement]
   , Names : V[SESSION*Name]
   , Prefixes : V[SESSION*Prefixed]
   ]
ENDCONTEXT