diff --git a/src/uml/create-diagram.ts b/src/uml/create-diagram.ts
index 94d0ff78..35631201 100644
--- a/src/uml/create-diagram.ts
+++ b/src/uml/create-diagram.ts
@@ -105,7 +105,7 @@ export async function createDiagramFromString(
     response = await request(url);
     const httpOK = 200;
     if (response.statusCode !== httpOK) {
-      Logger.error(`Plantuml Server responded with an error.\n${response.statusMessage}`);
+      await Logger.error(`Plantuml Server responded with an error.\n${response.statusMessage}`);
       throw new Error('Response not okay');
     }
   } catch (e) {
diff --git a/src/uml/read-definitions.ts b/src/uml/read-definitions.ts
index 5714af35..d0dfffb1 100644
--- a/src/uml/read-definitions.ts
+++ b/src/uml/read-definitions.ts
@@ -93,7 +93,7 @@ export function readAsEnumDefinition(
   );
 
   // get enum values according to type
-  if (declaration.kindString === 'Enumeration' && declaration.children) {
+  if (declaration.kindString === 'Enumeration' && typeof declaration.children !== 'undefined') {
     // standard enumeration
     for (const child of declaration.children) {
       if (child.kindString === 'Enumeration member') {
@@ -154,7 +154,7 @@ function getTypeInformation(type: LightweightType): string[] {
 export function readAsClassDefinition(
   declaration: DeclarationReflection,
 ): LightweightClassDefinition {
-  let type = declaration.kindString ? declaration.kindString.toLowerCase() : '';
+  let type = typeof declaration.kindString !== 'undefined' ? declaration.kindString.toLowerCase() : '';
   type = (declaration.flags.isAbstract ? 'abstract ' : '') + type;
 
   const classDefinition: LightweightClassDefinition = new LightweightClassDefinition(
@@ -314,7 +314,7 @@ function readAsReferenceType(type: ReferenceType): LightweightType {
     const tempTypeReflection = type.reflection as DeclarationReflection;
     // interfaces and classes in a type are a sink, since their declaration are defined elsewhere
     if (
-      tempTypeReflection.kindString &&
+      typeof tempTypeReflection.kindString !== 'undefined' &&
       ['Interface', 'Class', 'Enumeration', 'Type alias'].indexOf(
         tempTypeReflection.kindString,
       ) > -1
@@ -383,7 +383,7 @@ function readAsUnionType(type: UnionType): LightweightType {
  */
 function readAsReflectionType(type: ReflectionType): LightweightType {
   const returnType: LightweightType = new LightweightType();
-  if (type.declaration.sources) {
+  if (typeof type.declaration.sources !== 'undefined') {
     const src = type.declaration.sources[0];
     Logger.warn(
       `${src.line} : ${src.fileName}: Reflection Type not recognized. Refactoring to explicit class is advised.`,