chore: add a lot of exception throwing and parameter checking to hologram (#300)

Author: Snabeldier

src/main/java/minevalley/core/api/utils/Hologram.java

@@ -2,6 +2,10 @@
 
 import minevalley.core.api.modifiers.LocationModifier;
 import minevalley.core.api.modifiers.VisibilityModifier;
+import org.jetbrains.annotations.Contract;
+
+import javax.annotation.Nonnegative;
+import javax.annotation.Nonnull;
 
 @SuppressWarnings("unused")
 public interface Hologram extends LocationModifier, VisibilityModifier {
@@ -11,24 +15,30 @@ public interface Hologram extends LocationModifier, VisibilityModifier {
      *
      * @return the lines of the hologram.
      */
+    @Nonnull
+    @Contract(pure = true)
     String[] getLines();
 
     /**
      * Returns the line at the specified index.
      *
      * @param line the index of the line.
      * @return the line at the specified index.
+     * @throws IndexOutOfBoundsException if the line is out of bounds.
      */
-    default String getLine(int line) {
+    @Contract(pure = true)
+    default String getLine(@Nonnegative int line) throws IndexOutOfBoundsException {
         return getLines()[line];
     }
 
     /**
      * Adds a line to the hologram.
      *
      * @param text the text of the line.
+     * @throws IllegalArgumentException if the text is null.
      */
-    default void addLine(String text) {
+    default void addLine(@Nonnull String text) throws IllegalArgumentException {
+        if (text == null) throw new IllegalArgumentException("The text cannot be null.");
         addLineAfter(getLines().length - 1, text);
     }
 
@@ -37,21 +47,26 @@ default void addLine(String text) {
      *
      * @param line the index of the line.
      * @param text the text of the line.
+     * @throws IndexOutOfBoundsException if the line is out of bounds.
+     * @throws IllegalArgumentException  if the text is null.
      */
-    void addLineAfter(int line, String text);
+    void addLineAfter(@Nonnegative int line, @Nonnull String text) throws IndexOutOfBoundsException, IllegalArgumentException;
 
     /**
      * Changes the line at the specified index.
      *
      * @param line the index of the line.
      * @param text the new text of the line.
+     * @throws IndexOutOfBoundsException if the line is out of bounds.
+     * @throws IllegalArgumentException  if the text is null.
      */
-    void changeLine(int line, String text);
+    void changeLine(@Nonnegative int line, @Nonnull String text) throws IndexOutOfBoundsException, IllegalArgumentException;
 
     /**
      * Removes the line at the specified index.
      *
      * @param line the index of the line.
+     * @throws IndexOutOfBoundsException if the line is out of bounds.
      */
-    void removeLine(int line);
+    void removeLine(@Nonnegative int line) throws IndexOutOfBoundsException;
 }