Compiler error for genhl

[PXshadow]

| Error: Compiler failure
   | Please submit an issue at https://github.com/HaxeFoundation/haxe/issues/new
   | Attach the following information:
   | Haxe: 5.0.0-alpha.1+c4868e5; OS type: unix;
   | File "src/generators/genhl.ml", line 773, characters 19-26
   | Called from file "src/generators/genhl.ml", line 698, characters 95-112
   | Called from file "src/generators/genhl.ml", line 789, characters 9-35
   | Called from file "src/generators/genhl.ml", line 711, characters 94-152
   | Called from file "src/generators/genhl.ml", line 3287, characters 10-36
   | Called from file "src/generators/genhl.ml", line 3536, characters 8-106
   | Called from file "list.ml", line 110, characters 12-15
   | Called from file "list.ml", line 110, characters 12-15
   | Called from file "src/generators/genhl.ml", line 4262, characters 1-24
   | Called from file "src/compiler/generate.ml", line 204, characters 3-32
   | Called from file "src/compiler/compiler.ml", line 408, characters 29-64
   | Called from file "src/compiler/compiler.ml", line 424, characters 1-5
   | Called from file "src/compiler/compiler.ml", line 462, characters 5-23
   | Called from file "src/compiler/compiler.ml", line 502, characters 2-131
   | Called from file "src/compiler/compiler.ml", line 476, characters 2-9
   | Called from file "src/compiler/compiler.ml", line 705, characters 5-43
   | Called from file "src/compiler/compiler.ml", line 717, characters 13-22
   | Called from file "src/compiler/server.ml", line 803, characters 1-39
   | Called from file "src/compiler/haxe.ml", line 53, characters 0-56
   | 

Context: this is now being outputted for every hl test on a CI runner of a new branch. Can get example code if needed.