Fix 'contloc out of spec' crash when continentalness < -1.2

src/main/java/world/bentobox/boxed/generators/biomes/AbstractSeedBiomeProvider.java

@@ -264,16 +264,17 @@ public static Biome getBiome(int h, int t, double we) {
     }
 
     /**
-     * Continental location by continentalness
+     * Continental location by continentalness. The outer bands are open-ended because
+     * vanilla noise can fall outside the nominal [-1.2, 1.0] range.
      */
-    private enum ContLoc {
-        MUSHROOM_FIELDS(-1.2, -1.05),
+    enum ContLoc {
+        MUSHROOM_FIELDS(Double.NEGATIVE_INFINITY, -1.05),
         DEEP_OCEAN(-1.05, -0.455),
         OCEAN(-0.455, -0.19),
         COAST(-0.19, -0.11),
         NEAR_INLAND(-0.11, 0.03),
         MID_INLAND(0.03, 0.3),
-        FAR_INLAND(0.3, 10.0);
+        FAR_INLAND(0.3, Double.POSITIVE_INFINITY);
 
         private double min;
         private double max;
@@ -283,7 +284,7 @@ private enum ContLoc {
             this.max = max;
         }
 
-        public static ContLoc getCont(double continentalness) {
+        static ContLoc getCont(double continentalness) {
             for (ContLoc c : ContLoc.values()) {
                 if (continentalness >= c.min && continentalness < c.max) {
                     return c;

src/test/java/world/bentobox/boxed/generators/biomes/ContLocTest.java

@@ -0,0 +1,38 @@
+package world.bentobox.boxed.generators.biomes;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+import world.bentobox.boxed.generators.biomes.AbstractSeedBiomeProvider.ContLoc;
+
+/**
+ * Tests {@link ContLoc#getCont(double)} band lookup, including values outside the nominal
+ * continentalness range that vanilla noise can produce.
+ */
+class ContLocTest {
+
+    @Test
+    void testBelowNominalRangeIsMushroomFields() {
+        // Value seen in the wild that used to throw "contloc out of spec"
+        assertEquals(ContLoc.MUSHROOM_FIELDS, ContLoc.getCont(-1.2687000036239624));
+        assertEquals(ContLoc.MUSHROOM_FIELDS, ContLoc.getCont(-100D));
+    }
+
+    @Test
+    void testAboveNominalRangeIsFarInland() {
+        assertEquals(ContLoc.FAR_INLAND, ContLoc.getCont(10D));
+        assertEquals(ContLoc.FAR_INLAND, ContLoc.getCont(100D));
+    }
+
+    @Test
+    void testBandBoundaries() {
+        assertEquals(ContLoc.MUSHROOM_FIELDS, ContLoc.getCont(-1.2));
+        assertEquals(ContLoc.DEEP_OCEAN, ContLoc.getCont(-1.05));
+        assertEquals(ContLoc.OCEAN, ContLoc.getCont(-0.455));
+        assertEquals(ContLoc.COAST, ContLoc.getCont(-0.19));
+        assertEquals(ContLoc.NEAR_INLAND, ContLoc.getCont(-0.11));
+        assertEquals(ContLoc.MID_INLAND, ContLoc.getCont(0.03));
+        assertEquals(ContLoc.FAR_INLAND, ContLoc.getCont(0.3));
+    }
+}