Accents package incompatible with bm?

Question

Reading egreg's answer to Decrease length of underline in math, I wanted to use the accents package for lower bars in math mode.

It seem however that the package is incompatible with the bm package. When I add \usepackage{accents} to my preamble, even without using any commands related to the package, I get error messages for all my uses of \bm.

Missing number, treated as zero ...s when only one specific $\bm{\tilde{a}}

Missing control sequence inserted ...s when only one specific $\bm{\tilde{a}}

Missing } inserted ...s when only one specific $\bm{\tilde{a}}

Missing } inserted ...s when only one specific $\bm{\tilde{a}}

Missing } inserted ...s when only one specific $\bm{\tilde{a}}

Missing } inserted ...s when only one specific $\bm{\tilde{a}}

Extra }, or forgotten \endgroup ...s when only one specific $\bm{\tilde{a}}

Missing control sequence inserted ...s when only one specific $\bm{\tilde{a}}

Parameters must be numbered consecutively ...s when only one specific $\bm{\tilde{a}}

Missing number, treated as zero ... \leq \left| \sum_{a_i \in \bm{\tilde{a}}

Missing control sequence inserted ... \leq \left| \sum_{a_i \in \bm{\tilde{a}}

Missing } inserted ... \leq \left| \sum_{a_i \in \bm{\tilde{a}}

Extra }, or forgotten \endgroup ... \leq \left| \sum_{a_i \in \bm{\tilde{a}}

Missing control sequence inserted ... \leq \left| \sum_{a_i \in \bm{\tilde{a}}

Parameters must be numbered consecutively ... \leq \left| \sum_{a_i \in \bm{\tilde{a}}

Missing number, treated as zero for any $\bm{\tilde{a}}

Missing control sequence inserted for any $\bm{\tilde{a}}

Missing } inserted for any $\bm{\tilde{a}}

Extra }, or forgotten \endgroup for any $\bm{\tilde{a}}

Missing control sequence inserted for any $\bm{\tilde{a}}

Parameters must be numbered consecutively for any $\bm{\tilde{a}}

Missing number, treated as zero ...he case in particular for $\bm{\tilde{a}}

Missing control sequence inserted ...he case in particular for $\bm{\tilde{a}}

Missing } inserted ...he case in particular for $\bm{\tilde{a}}

Extra }, or forgotten \endgroup ...he case in particular for $\bm{\tilde{a}}

Missing control sequence inserted ...he case in particular for $\bm{\tilde{a}}

Parameters must be numbered consecutively ...he case in particular for $\bm{\tilde{a}}

Is there a way to make both packages compatible?

Answer 1

Instead of $\bm{\tilde{a}}$, use $\tilde{\bm{a}}$.

OR

Use $\bm{{\tilde{a}}}$, an extra grouping inside \bm{{...}}.