fix tokenizing of numbers and expressions of offset

src/Language/Wasm/Lexer.x

@@ -33,8 +33,8 @@ $doublequote = \"
 @linecomment = ";;" $linechar* \x0A
 @startblockcomment = "(;"
 @endblockcomment = ";)"
-@num = $digit (\_? $digit*)
+@num = $digit (\_? $digit*)*
-@hexnum = $hexdigit (\_? $hexdigit*)
+@hexnum = $hexdigit (\_? $hexdigit*)*
 @id = "$" $idchar+
 @floatfrac = @num "." (@num)?
 @exp = [Ee] $sign? @num

src/Language/Wasm/Parser.y

@@ -960,7 +960,7 @@ start :: { StartFunction }
 -- but collection of testcases omits 'offset' in this position
 -- I am going to support both options for now, but maybe it has to be updated in future.
 offsetexpr :: { [Instruction] }
-    : 'offset' foldedinstr ')' { $2 }
+    : 'offset' list(foldedinstr) ')' { concat $2 }
     | foldedinstr1 { $1 }
 
 elemsegment :: { ElemSegment }