Bug when y ~ 0 + Intercept & family = 'poisson' & sample_prior = 'yes'

[bfordAIMS]

# REPREX
library(brms)

data <- data.frame(count = rpois(1000, 0.05))

m1 <- brm(
  formula = "count ~ 1",
  family = "poisson", 
  sample_prior = "yes",
  data = data
)
m2 <- brm(
  formula = "count ~ 0 + Intercept",
  family = "poisson",
  sample_prior = "yes",
  data = data
)
m3 <- brm(
  formula = "count ~ 0 + Intercept",
  family = "poisson",
  sample_prior = "no",
  data = data
)
m4 <- brm(
  formula = "count ~ 0 + Intercept",
  family = "negbinomial",
  sample_prior = "yes",
  data = data
)
m5 <- brm(
  formula = "count ~ 0 + Intercept",
  family = "gaussian",
  sample_prior = "yes",
  data = data
)

In the above reprex, I fit four intercept-only models for the same data. The models have different combinations of (1) intercept specification: ~ 1 vs ~ 0 + Intercept; (2) family: poisson vs negbinomial vs gaussian; (3) sample_prior = 'yes' vs 'no'. Models m1, m3, m4, and m5 all compile as expected, however, m2 returns the error

Error in strsplit(gsub(" |\\n", "", tpar_prior), ";")[[1]] : 
  subscript out of bounds

this is the specific combination of y ~ 0 + Intercept & family = "poisson" & sample_prior = "yes".