Hold a reference to the temporary proplist used in case of script errors

The parser does not know whether the constant proplist it is about to fill
is missing because it was overwritten by a later local/constant, or because
the preparser was interrupted by a script error and didn't store its
proplist. Thus, the parser cannot simply give up at that point, and in
order to keep things simple it creates a throwaway proplist. This proplist
was thrown away too soon, though.

Thanks to Zapper for the testcase.

Conflicts:
	src/script/C4AulParse.cpp

planet/Tests.ocf/ScriptError1.ocs/Scenario.txt

@@ -0,0 +1 @@
+ 

planet/Tests.ocf/ScriptError1.ocs/Script.c

@@ -0,0 +1,28 @@
+local MENU =
+{
+	left = 
+	{
+		Wdt = 500,
+		title = 
+		{
+			Wdt = 500,
+			Decoration = GUI_MenuDeco
+		}
+	},
+	
+	right =
+	{
+		X = 500,
+		objects = 
+		{
+			o1 = {Symbol = Rock, X = [0, 50], Y = [0, 40], Wdt = [0, 50 ERROR HERE! 64], Hgt=[0, 40 + 64]},
+			o2 = {Symbol = Gold, X = [500, 50 - 32], Y = [500, 40 - 32], Wdt = [500, 50 +32], Hgt = [500, 40 + 32]},
+			o3 = {Symbol = Wood, X = [1000, -64], Y = [1000, -64], Wdt = [1000, 0], Hgt = [500, 0]},
+		},
+		text =
+		{
+			Y = [1000, -300],
+			Hgt = 1000
+		}
+	}
+};

src/script/C4AulParse.cpp

@@ -1948,6 +1948,7 @@ void C4AulParse::Parse_PropList()
 
 C4Value C4AulParse::Parse_ConstPropList(const C4PropListStatic * parent, C4String * Name)
 {
+	C4Value v;
 	if (!Name)
 		throw new C4AulParseError(this, "a static proplist is not allowed to be anonymous");
 	C4PropListStatic * p;
@@ -1957,7 +1958,6 @@ C4Value C4AulParse::Parse_ConstPropList(const C4PropListStatic * parent, C4Strin
 	}
 	else
 	{
-		C4Value v;
 		bool r;
 		if (parent)
 			r = parent->GetPropertyByS(Name, &v);
@@ -1966,7 +1966,7 @@ C4Value C4AulParse::Parse_ConstPropList(const C4PropListStatic * parent, C4Strin
 		if (!r || !v.getPropList())
 		{
 			// the proplist couldn't be parsed or was overwritten by a later constant.
-			// create a temporary replacement
+			// create a temporary replacement, make v hold the reference to it for now
 			v.SetPropList(C4PropList::NewAnon(NULL, parent, Name));
 		}
 		p = v.getPropList()->IsStatic();