Add test

docs/src/notebooks/example.jl

@@ -35,7 +35,7 @@ For example, $x = 3\pi$ and
 y = \frac{a \cdot b}{c^2}
 ```
 
-For using the dollar symbol normally, escape it with a leading backslash just like in Pluto:
+For using the dollar symbol normally, escape it with a backslash just like in Pluto:
 ```markdown
 The prices were \$5 and \$10.
 ```

src/html.jl

@@ -138,7 +138,7 @@ end
 
 function _patch_dollar_symbols(body::String)::String
     lines = split(body, '\n')
-    # Pluto wraps inline HTML in a tex class, so if we see a dollar symbol in a plain text output,
+    # Pluto wraps inline LaTeX in a tex class, so if we see a dollar symbol in a plain text output,
     # we should escape it since it is not a LaTeX expression.
     for i in 1:length(lines)
         line = lines[i]

src/output.jl

@@ -177,15 +177,19 @@ function _throw_if_error(session::ServerSession, nb::Notebook)
             filename = _indent(nb.path)
             code = _indent(cell.code)
             body = cell.output.body::Dict{Symbol,Any}
-            msg = body[:msg]::String
-            error_text::String = if body[:stacktrace] isa CapturedException
-                val = body[:stacktrace]::CapturedException
-                io = IOBuffer()
-                ioc = IOContext(io, :color => Base.get_have_color())
-                showerror(ioc, val)
-                _indent(String(take!(io)))
+            error_text::String = if haskey(body, :stacktrace)
+                if body[:stacktrace] isa CapturedException
+                    val = body[:stacktrace]::CapturedException
+                    io = IOBuffer()
+                    ioc = IOContext(io, :color => Base.get_have_color())
+                    showerror(ioc, val)
+                    _indent(String(take!(io)))
+                else
+                    _indent(string(body[:stacktrace])::String)
+                end
             else
-                _indent(string(body[:stacktrace])::String)
+                # Fallback.
+                string(body)::String
             end
             msg = """
                 Execution of notebook failed.

test/html.jl

@@ -243,3 +243,25 @@ end
     ])
     html, _ = notebook2html_helper(nb; use_distributed=false)
 end
+
+@testset "patch_dollar_symbols" begin
+    nb = Notebook([
+        Cell(raw"""
+        md\"\"\"
+        # Foo
+
+        ```markdown
+        The prices are \$4 and \$5.
+        ```
+        The prices are \$10 and \$20.
+
+        But this is math $x$.
+        \"\"\"
+        """)
+    ])
+    html, _ = notebook2html_helper(nb; use_distributed=false)
+    # Verify that inline math is converted to `<span class="tex">` by Pluto.
+    @test contains(html, raw"But this is math <span class=\"tex\">$x$</span>.")
+    @test contains(html, raw"The prices are \$4 and \$5")
+    @test contains(html, raw"The prices are \$10 and \$20")
+end