btree/rangemap: CamelCase the error names

src/util/btree.zig

@@ -16,7 +16,7 @@ pub fn BTree(comptime N: type, comptime compare_fn: CompareFn(N), comptime deini
         gpa: Allocator,
         root: ?*Node = null,
 
-        pub const Error = error{ already_exists, does_not_exist } || Allocator.Error;
+        pub const Error = error{ AlreadyExists, DoesNotExist } || Allocator.Error;
 
         pub fn WalkFn(comptime C: type) type {
             return fn (*const Node, C) void;
@@ -94,7 +94,7 @@ pub fn BTree(comptime N: type, comptime compare_fn: CompareFn(N), comptime deini
                             child.parent = n;
                             n.left = child;
                         },
-                        .eq => return error.already_exists,
+                        .eq => return error.AlreadyExists,
                     }
                     return .{ n, inserted };
                 } else {
@@ -161,7 +161,7 @@ pub fn BTree(comptime N: type, comptime compare_fn: CompareFn(N), comptime deini
                     }
                     return node;
                 } else {
-                    return error.does_not_exist;
+                    return error.DoesNotExist;
                 }
             }
 

src/util/rangemap.zig

@@ -210,7 +210,7 @@ test "Range map insertion" {
     _ = try map.insert(0, 10, "Range 1");
     _ = try map.insert(20, 10, "Range 3");
 
-    try std.testing.expectError(error.already_exists, map.insert(5, 10, "Invalid range"));
+    try std.testing.expectError(error.AlreadyExists, map.insert(5, 10, "Invalid range"));
 
     _ = try map.insert(1000, 10, "Range 4");
 }