Fix function calling and improve error with single list params (SkriptLang#8096)

Author: Efnilite

src/main/java/ch/njol/skript/lang/function/FunctionReference.java

@@ -7,6 +7,7 @@
 import ch.njol.skript.lang.*;
 import ch.njol.skript.lang.function.FunctionRegistry.Retrieval;
 import ch.njol.skript.lang.function.FunctionRegistry.RetrievalResult;
+import ch.njol.skript.lang.parser.ParserInstance;
 import ch.njol.skript.log.RetainingLogHandler;
 import ch.njol.skript.log.SkriptLogger;
 import ch.njol.skript.registrations.Classes;
@@ -323,6 +324,7 @@ private Function<?> getRegisteredFunction() {
 		}
 
 		Retrieval<Function<?>> attempt = FunctionRegistry.getRegistry().getFunction(script, functionName, parameterTypes);
+
 		if (attempt.result() == RetrievalResult.EXACT) {
 			return attempt.retrieved();
 		}

src/main/java/ch/njol/skript/lang/function/FunctionRegistry.java

@@ -475,7 +475,8 @@ private Retrieval<Signature<?>> getSignature(@NotNull NamespaceIdentifier namesp
 					}
 				}
 
-				return Set.of(candidate);
+				candidates.add(candidate);
+				continue;
 			}
 
 			// if argument counts are not possible, skip

src/test/skript/tests/misc/function overloading.sk

@@ -85,3 +85,19 @@ parse:
 test "function overloading with supertype":
 	assert {FunctionOverloadingSupertype1::parse::*} is not set
 	assert {FunctionOverloadingSupertype2::parse::*} is not set
+
+function overloading_listarg(x: int, y: int) :: int:
+	return 1
+
+function overloading_listarg(x: int, y: int, z: int) :: int:
+	return 2
+
+function overloading_listarg(x: ints) :: int:
+	return 3
+
+test "function overloading with single param lists":
+	assert overloading_listarg(1) = 3
+	assert overloading_listarg(1, 2) = 1
+	assert overloading_listarg(1, 2, 3) = 2
+	assert overloading_listarg(1, 2, 3, 4) = 3
+	assert overloading_listarg(1, 2, 3, 4, 5) = 3