Add not null preconditions for some info classes (#8235)

Author: sovdeeth

src/main/java/org/skriptlang/skript/lang/arithmetic/OperationInfo.java

@@ -1,6 +1,8 @@
 package org.skriptlang.skript.lang.arithmetic;
 
 import com.google.common.base.MoreObjects;
+import com.google.common.base.Preconditions;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.skriptlang.skript.lang.converter.Converters;
 
@@ -16,7 +18,16 @@ public class OperationInfo<L, R, T> {
 	private final Class<T> returnType;
 	private final Operation<L, R, T> operation;
 
-	public OperationInfo(Class<L> left, Class<R> right, Class<T> returnType, Operation<L, R, T> operation) {
+	public OperationInfo(
+		@NotNull Class<L> left,
+		@NotNull Class<R> right,
+		@NotNull Class<T> returnType,
+		@NotNull Operation<L, R, T> operation
+	) {
+		Preconditions.checkNotNull(left, "Cannot do arithmetic with nothing and something! (left is null)");
+		Preconditions.checkNotNull(right, "Cannot do arithmetic with something and nothing! (right is null)");
+		Preconditions.checkNotNull(returnType, "Cannot have nothing as the result of arithmetic! (returnType is null)");
+		Preconditions.checkNotNull(operation, "Cannot do arithmetic with a null operation!");
 		this.left = left;
 		this.right = right;
 		this.returnType = returnType;

src/main/java/org/skriptlang/skript/lang/comparator/ComparatorInfo.java

@@ -1,5 +1,8 @@
 package org.skriptlang.skript.lang.comparator;
 
+import com.google.common.base.Preconditions;
+import org.jetbrains.annotations.NotNull;
+
 /**
  * Holds information about a Comparator.
  *
@@ -12,7 +15,14 @@ public final class ComparatorInfo<T1, T2> {
 	private final Class<T2> secondType;
 	private final Comparator<T1, T2> comparator;
 
-	ComparatorInfo(Class<T1> firstType, Class<T2> secondType, Comparator<T1, T2> comparator) {
+	ComparatorInfo(
+		@NotNull Class<T1> firstType,
+		@NotNull Class<T2> secondType,
+		@NotNull Comparator<T1, T2> comparator
+	) {
+		Preconditions.checkNotNull(firstType, "Cannot create a comparison between nothing and something! (firstType is null)");
+		Preconditions.checkNotNull(secondType, "Cannot create a comparison between something and nothing! (secondType is null)");
+		Preconditions.checkNotNull(comparator, "Cannot create a comparison with a null comparator!");
 		this.firstType = firstType;
 		this.secondType = secondType;
 		this.comparator = comparator;

src/main/java/org/skriptlang/skript/lang/converter/ConverterInfo.java

@@ -1,5 +1,8 @@
 package org.skriptlang.skript.lang.converter;
 
+import com.google.common.base.Preconditions;
+import org.jetbrains.annotations.NotNull;
+
 /**
  * Holds information about a {@link Converter}.
  *
@@ -13,7 +16,15 @@ public final class ConverterInfo<F, T> {
 	private final Converter<F, T> converter;
 	private final int flags;
 
-	public ConverterInfo(Class<F> from, Class<T> to, Converter<F, T> converter, int flags) {
+	public ConverterInfo(
+		@NotNull Class<F> from,
+		@NotNull Class<T> to,
+		@NotNull Converter<F, T> converter,
+		int flags
+	) {
+		Preconditions.checkNotNull(from, "Cannot convert from nothing to something! (from is null)");
+		Preconditions.checkNotNull(to, "Cannot convert from something to nothing! (to is null)");
+		Preconditions.checkNotNull(converter, "Cannot convert using a null converter!");
 		this.from = from;
 		this.to = to;
 		this.converter = converter;