fixed logo handling and added existence checks

leibnizfh.cls

@@ -118,6 +118,21 @@
 	\setlength{\parindent}{0pt} % Absatzeinrückung
 	\setlength{\parskip}{11pt} % Absatzhöhe
 
+% Helpercommandos
+	% Logo
+	\newcommand{\lfh@includeLogo}{%
+		    \ifx\lfh@logo\@empty
+		        \ClassInfo{leibnizfh}{No logo file specified. Use \protect\lfhsetup{logo=path/to/file.ext}}%
+    \else
+        	\IfFileExists{\lfh@logo}{%
+            	\includegraphics[height=3\baselineskip]{\lfh@logo}%
+        	}{%
+            	\ClassWarning{leibnizfh}{Logo file '\lfh@logo' not found. Header rendered without logo}%
+        	}%
+    	\fi
+	}
+
+
 % Fußnote
 	\renewcommand\footnotesize{%
 		\@setfontsize\footnotesize{9pt}{11pt} }
@@ -137,7 +152,7 @@
 	\newcommand*\lfh@headerone{Muster}
 	\newcommand*\lfh@headertwo{Haus-\, Seminararbeiten\, Praxisreflexionen\, Essays…}
 	\newcommand*\lfh@headerthree{Leibniz-Fachhochschule $\cdot$ Version 2025}
-	\newcommand*\lfh@logo{logo-lfh}
+	\newcommand*\lfh@logo{}
 
 	\define@key{lfh}{title}{\def\lfh@title{#1}}
 	\define@key{lfh}{subtitle}{\def\lfh@subtitle{#1}}
@@ -149,6 +164,7 @@
 	\define@key{lfh}{email}{\def\lfh@email{#1}}
 	\define@key{lfh}{prof}{\def\lfh@prof{#1}}
 	\define@key{lfh}{program}{\def\lfh@program{#1}}
+	\define@key{lfh}{logo}{\def\lfh@logo{#1}}
 	\define@key{lfh}{submission}{\def\lfh@submission{#1}}
 	\define@key{lfh}{headerone}{\def\lfh@headerone{#1}}
 	\define@key{lfh}{headertwo}{\def\lfh@headertwo{#1}}
@@ -172,7 +188,7 @@
 				\textbf{\fontsize{10}{12}\selectfont \lfh@headertwo}\\
 				\fontsize{10}{12}\selectfont \lfh@headerthree
 			}
-			\IfFileExists{\lfh@logo}{\fancyhead[R]{\includegraphics[height=3\baselineskip]{\lfh@logo}}}{}
+			\fancyhead[R]{\lfh@includeLogo}
 			\renewcommand{\headrulewidth}{0.4pt}
 			\renewcommand{\footrulewidth}{0pt}
 			}