[texworks] Is this my error or of TeXworks?

[mail at heinzebert.de]

To Whom it may concern
The caption part of following statements generates several error  
messages by using pdfLaTeX:

\begin{figure}[htbp]
   \centering
   \includegraphics[scale=0.5]{CollatzTree.pdf}
   \caption{Grid graph representation of the tree  
${\boldsymbol{A}}_{\overrightarrow{C}}(1)$. The map  
$\overrightarrow{C}$ is the generating function.}
   \label{fig:FT}
\end{figure}

But after skipping every message by entering 'return' the desired  
output of the caption is achieved.

TeXworks 2019 version 0.6.3(travis-ci) [r.a2470ca, 16.03.2019 18:06]
Windows 8 professional 64Bit version

With many thanks for your efforts and kind regards
Heinz Ebert