Avoid stringHead of an empty string

Author: krame505

src/Libraries/Base1/Prelude.bs

@@ -4530,7 +4530,9 @@ instance (SplitPorts a p, TupleSize p n, WrapPorts p pb, WrapMethod b v, Curry (
 
   methodArgBaseNames _ prefix (Cons h t) i = Cons
     -- arg_names can start with a digit
-    (if prefix == "" && not (isDigit $ stringHead h) then h else prefix +++ "_" +++ h)
+    (if prefix == "" && (h == "" || not (isDigit $ stringHead h))
+     then h
+     else prefix +++ "_" +++ h)
     (methodArgBaseNames (_ :: b) prefix t $ i + 1)
   methodArgBaseNames _ prefix Nil i = Cons
     (prefix +++ "_" +++ integerToString i)

src/Libraries/Base1/SplitPorts.bs

@@ -69,7 +69,7 @@ instance (ShallowSplitPorts' r p) => ShallowSplitPorts' (Meta (MetaField name id
   shallowUnsplitPorts' = Meta ∘ shallowUnsplitPorts'
   shallowSplitPortNames' _ base = shallowSplitPortNames' (_ :: r) $
     -- Avoid an extra underscore, since data fields names are _[0-9]+
-    if stringHead (stringOf name) == '_'
+    if stringOf name == "" || stringHead (stringOf name) == '_'
     then base +++ stringOf name
     else base +++ "_" +++ stringOf name
 
@@ -180,7 +180,7 @@ instance (DeepSplitPorts'' r p) => DeepSplitPorts'' (Meta (MetaField name idx) r
   deepUnsplitPorts'' = Meta ∘ deepUnsplitPorts''
   deepSplitPortNames'' _ base = deepSplitPortNames'' (_ :: r) $
     -- Avoid an extra underscore, since data fields names are _[0-9]+
-    if stringHead (stringOf name) == '_'
+    if stringOf name == "" || stringHead (stringOf name) == '_'
     then base +++ stringOf name
     else base +++ "_" +++ stringOf name