[js] Fix coercions with int8

Author: pmurias

src/vm/js/Compiler.nqp

@@ -597,7 +597,7 @@ class QAST::CompilerJS does DWIMYNameMangling does SerializeOnce {
                     return Chunk.new($desired, "{$chunk.expr}.\$\$decont($*CTX).\$\$toBool($*CTX)", $chunk);
                 }
 
-                return QAST::OperationsJS.unbox($*HLL, $desired, $chunk);
+                return QAST::OperationsJS.unbox(self, $*HLL, $desired, $chunk);
             }
 
             if $desired == $T_STR {
@@ -637,6 +637,7 @@ class QAST::CompilerJS does DWIMYNameMangling does SerializeOnce {
                     %convert{$T_INT16} := 'intToObj';
                     %convert{$T_NUM} := 'numToObj';
                     %convert{$T_STR} := 'strToObj';
+                    nqp::die("Can't coerce $got to OBJ") unless nqp::existskey(%convert, $got);
                     return Chunk.new($T_OBJ, "nqp.{%convert{$got}}(HLL, {$chunk.expr})", $chunk);
                 }
             }
@@ -653,7 +654,7 @@ class QAST::CompilerJS does DWIMYNameMangling does SerializeOnce {
 
             if $desired == $T_INT8 || $desired == $T_INT16 {
                 my $int_chunk := $got == $T_INT ?? $chunk !! self.coerce($chunk, $T_INT);
-                return Chunk.new($T_INT16, self.int_to_fancy_int($desired, $int_chunk.expr) , $int_chunk);
+                return Chunk.new($desired, self.int_to_fancy_int($desired, $int_chunk.expr) , $int_chunk);
             }
 
             return Chunk.new($desired, "nqp.coercion($got, $desired, {$chunk.expr})") #TODO

src/vm/js/Operations.nqp

@@ -1799,15 +1799,24 @@ class QAST::OperationsJS {
         %hll_unbox{$hll}{$type} := $method_name;
     }
 
-    method unbox($hll, $desired, $chunk) {
+    method unbox($comp, $hll, $desired, $chunk) {
         if nqp::existskey(%hll_unbox, $hll) && nqp::existskey(%hll_unbox{$hll}, $desired) {
             return Chunk.new($desired, '(' ~ $chunk.expr ~ ").\$\${%hll_unbox{$hll}{$desired}}()", $chunk);
         }
         my %convert;
         %convert{$T_STR} := 'toStr';
         %convert{$T_NUM} := 'toNum';
         %convert{$T_INT} := 'toInt';
-        return Chunk.new($desired, 'nqp.' ~ %convert{$desired} ~ '(' ~ $chunk.expr ~ ", {$*CTX})", $chunk);
+        my int $is_fancy_int := $desired == $T_INT8 || $desired == $T_INT16;
+
+        nqp::die("Can't coerce OBJ to $desired") unless nqp::existskey(%convert, $desired) || $is_fancy_int;
+
+        my str $rough_convert := 'nqp.' ~ %convert{$is_fancy_int ?? $T_INT !! $desired} ~ '(' ~ $chunk.expr ~ ", {$*CTX})";
+        my str $convert := $is_fancy_int
+            ?? $comp.int_to_fancy_int($desired, $rough_convert)
+            !! $rough_convert;
+
+        return Chunk.new($desired, $convert, $chunk);
     }
 }