refactor: Prevent negated conditions

src/util/GuardedStream.ts

@@ -88,14 +88,14 @@ function emitStoredErrors(this: Guarded, event: string, func: (error: Error) =>
  */
 export function guardStream<T extends NodeJS.EventEmitter>(stream: T): Guarded<T> {
   const guarded = stream as Guarded<T>;
-  if (!isGuarded(stream)) {
-    guarded[guardedErrors] = [];
-    guarded.on('error', guardingErrorListener);
-    guarded.on('newListener', emitStoredErrors);
-  } else {
+  if (isGuarded(stream)) {
     // This makes sure the guarding error listener is the last one in the list again
     guarded.removeListener('error', guardingErrorListener);
     guarded.on('error', guardingErrorListener);
+  } else {
+    guarded[guardedErrors] = [];
+    guarded.on('error', guardingErrorListener);
+    guarded.on('newListener', emitStoredErrors);
   }
   return guarded;
 }

src/util/PathUtil.ts

@@ -139,7 +139,7 @@ function transformPathComponents(path: string, transform: (part: string) => stri
     .map((part, index): string =>
       index % 2 === 0 ? transform(part) : part.toUpperCase())
     .join('');
-  return !queryString ? transformed : `${transformed}${queryString}`;
+  return queryString ? `${transformed}${queryString}` : transformed;
 }
 
 /**

src/util/QuadUtil.ts

@@ -72,8 +72,8 @@ export class FilterPattern {
    * @param object - Optionally filter based on a specific object.
    */
   public constructor(subject?: string, predicate?: string, object?: string) {
-    this.subject = typeof subject !== 'undefined' ? toNamedTerm(subject) : null;
-    this.predicate = typeof predicate !== 'undefined' ? toNamedTerm(predicate) : null;
-    this.object = typeof object !== 'undefined' ? toNamedTerm(object) : null;
+    this.subject = typeof subject === 'string' ? toNamedTerm(subject) : null;
+    this.predicate = typeof predicate === 'string' ? toNamedTerm(predicate) : null;
+    this.object = typeof object === 'string' ? toNamedTerm(object) : null;
   }
 }

src/util/SliceStream.ts

@@ -31,11 +31,11 @@ export class SliceStream extends Transform {
     let start = options.start;
     const end = options.end ?? Number.POSITIVE_INFINITY;
     if (options.start < 0) {
-      if (typeof options.size !== 'number') {
-        throw new RangeNotSatisfiedHttpError('Slicing data at the end of a stream requires a known size.');
-      } else {
+      if (typeof options.size === 'number') {
         // `start` is a negative number here so need to add
         start = options.size + start;
+      } else {
+        throw new RangeNotSatisfiedHttpError('Slicing data at the end of a stream requires a known size.');
       }
     }